Hundreds of hidden cameras filmed around the clock, the network said. Few people knew of the project. Guards and inmates were in the dark.

There are gritty, bloody scenes of fights, drug use and confrontations between real inmates and the posing volunteers.

At one point, a weeping female volunteer says she has had enough.

The civilians, who have never been charged with a crime, include a police officer, a social worker and a military wife.

Their reasons varied for volunteering, but they shared the goal of "leaving with a better understanding of the system — how it operates, its psychological effects, and wanting a part in exposing its larger impact on society," the network said in a press release.